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| Titel |
Characterization of submicron aerosols during a month of serious pollution in Beijing, 2013 |
| VerfasserIn |
J. K. Zhang, Y. Sun, Z. R. Liu, D. S. Ji, B. Hu, Q. Liu, Y. S. Wang |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 14, no. 6 ; Nr. 14, no. 6 (2014-03-20), S.2887-2903 |
| Datensatznummer |
250118517
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| Publikation (Nr.) |
 copernicus.org/acp-14-2887-2014.pdf |
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| Zusammenfassung |
In January 2013, Beijing experienced several serious haze events. To achieve
a better understanding of the characteristics, sources and processes of
aerosols during this month, an Aerodyne high-resolution time-of-flight
aerosol mass spectrometer (HR-ToF-AMS) was deployed at an urban site between
1 January and 1 February 2013 to obtain the size-resolved chemical
composition of non-refractory submicron particles (NR-PM1). During this
period, the mean measured NR-PM1 mass concentration was
89.3 ± 85.6 μg m−3, and it peaked at 423 μg m−3. Positive
matrix factorization (PMF) differentiated the organic aerosol into five
components, including a highly oxidized, low-volatility oxygenated organic
aerosol (LV-OOA), a less oxidized, semi-volatile oxygenated OA (SV-OOA), a
coal combustion OA (CCOA), a cooking-related OA (COA), and a
hydrocarbon-like OA (HOA), which on average accounted for 28%, 26%,
15%, 20% and 11% of the total organic mass, respectively.
A detailed comparison between the polluted days and unpolluted days found
many interesting results. First, the organic fraction was the most important
NR-PM1 species during the unpolluted days (58%), while inorganic
species were dominant on polluted days (59%). The OA composition also
experienced a significant change; it was dominated by primary OA (POA),
including COA, HOA and CCOA, on unpolluted days. The contribution of
secondary OA (SOA) increased from 35% to 63% between unpolluted and
polluted days. Second, meteorological effects played an important role in
the heavy pollution in this month and differed significantly between the two
types of days. The temperature and relative humidity (RH) were all increased
on polluted days and the wind speed and air pressure were decreased. Third,
the diurnal variation trend in NR-PM1 species and OA components showed
some differences between the two types of days, and the OA was more highly
oxidized on polluted days. Fourth, the effects of air masses were
significantly different between the two types of days; air was mainly
transported from contaminated areas on the polluted days. The comparison
also found that the aerosol was more acidic on polluted days. Additionally,
the variation trends of the mass concentration and mass fractions of
NR-PM1 species and OA components were more dramatic when the
NR-PM1 mass loading was at a higher level. The serious pollution
observed in this month can be attributed to the synergy of unfavorable
meteorological factors, the transport of air masses from high-pollution
areas, emission by local sources, and other factors. |
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